1. Technical Field
The present invention relates to an improved apparatus to seal the sides of the nip area at the sides of opposing sheeter rollers generally mounted parallel to each other. An improved seal prevents doughy material from penetrating into crevices of the apparatus according to the prior art as doughy material is compressed into a sheet. Specifically, this invention uses improved materials and configurations to create a new side seal for a sheeting apparatus.
2. Description of Related Art
With reference to FIG. 1, in a conventional dough sheeter, opposing rollers 110 are separated by a small gap or nip 102. Doughy material 104 is fed into the nip 102 above opposing rollers 110 and passes through the nip 102 to form a sheet 106. It is normally necessary to place a seal at the ends of opposing sheeter rollers to prevent leakage of doughy material from the sides of opposing rollers 110. Leakage results in loss of valuable product as well as thinning of the dough sheet near the edges.
FIG. 2 shows an overhead view of conventional side seals. With reference to FIG. 2, side seals 210 are typically made of a plastic or other low-friction material, and are pressed against the ends of sheeting rollers 110 by mechanical means including, but not limited to, screws 204 attached to a sheeter housing 206. Such side seals 210 press with a force greater than the pressure created by the sheeting process. There are several drawbacks to conventional arrangements including seal leakage, seal wear due to pressurized contact, and poor accessibility for seal replacement.
FIG. 3a is a cross-sectional drawing of a portion of a prior art side seal. Such a side seal according to the prior art consists of a side seal bracket 320 of arbitrary shape made of metal or other stiff material, a shim 312 also made of a metal or other stiff material, and a plastic sealing piece 308. FIG. 3a shows such a portion of a side seal after newly assembled and before operation of a sheeting apparatus. The shim 312 is held in place by one or more screws 314.
Often, manual adjustment of the side seal is required to obtain the desired distance between the plastic sealing piece 308 and the sheeting rollers 512, 514. Generally, the shims 312 and screws 314 must be manually adjusted to bring the sealing pieces 308 within about 0.05 inches (1.27 mm) to 0.07 inches (1.78 mm) of the side surface of the sheeting rollers 512, 514 along the length of the sealing piece 308. According to some embodiments of the prior art, such adjustment may require up to twelve hours of manual adjustment each time the seals are replaced. According to the prior art, side seals wear out within about one month of continuous sheeting operation.
With reference to FIG. 3a, when the side seal is assembled, the shim 312 and plastic sealing piece 308 are tightly abutted to each other, and the plastic sealing piece 308 is uniform having no wear. FIG. 3b is a similar cross-sectional drawing showing the same pieces of a side seal after having been subjected to approximately one month of continuous operation and wear. Over time, doughy material 104 is forced into the interface between the plastic sealing piece 308 and the metal shim 312 by the operating or sheeting pressure generated by opposing sheeting rollers 512, 514. As seen in FIG. 3b, repeated penetration of doughy material 104 between the sealing piece 308 and the metal shim 312 has forced the plastic sealing piece 308 to bulge outward toward the sheeting rollers 110. This has caused the plastic sealing piece 308 to wear away and to be replaced by doughy material 104 although still maintaining a relatively flat outer surface 402. Over time, the thickness of the plastic sealing piece 308 remains thicker near the attaching screw 310. If the plastic sealing piece 308 is not replaced, the side seal eventually becomes ineffective.
Consequently, a need exists for an improved apparatus to provide for more effective sealing of the sides of a dough sheeter and less waste of doughy material. A need exists to eliminate the required manual adjustment necessary to replace plastic sealing pieces. A need exists for an apparatus that allows for easier, faster installation of replacement side sealing pieces. A further need exists to eliminate plastic sealing material from entering sheeted dough as the plastic sealing piece is worn away during sheeting operation. Additionally, a need exists to reduce the frequency of replacing worn plastic sealing pieces.